Rapid changes in the healthcare marketplace have led to an increased reliance upon telephone interactions provide medical advice and control patient demand for medical care. This form of "gatekeeping" is referred to as telephone triage or demand management. In this model, rather than speaking with a physician on-call, the patient calls a medical advice service, usually staffed by a nurse, who recommends the appropriate level and timing of medical care. The potential for reduction in costs has led to the widespread contracting of commercial triage services by health providers and third-party payors. Little research has been done to evaluate this process. The study objective is to compare the telephone triage of a commercial service (experimental) versus a traditional physician on-call (control) in a prospective, randomized trial of pediatric patients, who represent the majority of calls for medical advice. The outcome measures (dependent variables) include 1) the occurrence of unadvised and significant medical care, 2) preventable adverse outcomes, 3) cost of care, and 4) patient satisfaction. Unadvised and significant medical care occurs when a patient receives significant medical care prior to the timing of care explicitly recommended by the telephone advice. Preventable adverse outcomes include death, disability, and hospitalization that could have been prevented if the telephone triage provider had recommended a higher level of care. Cost of care includes the cost of providing telephone advice plus the cost of all emergency department, clinic, hospital, and physician costs. The study population will be the patients of the UCLA Department of General Pediatrics. All calls for medical advice after-hours will be forwarded to the Study Call Center. After consent and randomization, the call will be directed either to the physician on-call or to Access Health, the largest provider of commercial telephone triage advice. Data collection will consist of a follow-up telephone interview of all callers, and a review of the medical and billing records of all patients who visit the emergency department or clinic within 72 hours of their initial call. An estimated 1,686 patients will be enrolled in the study over a 6 month time period.